Longitudinal clinical studies with antimicrobial mouthrinses.

This chapter examines the use of long-term clinical studies to evaluate the effectiveness of antimicrobial mouthrinses in the prevention and/or treatment of plaque and gingivitis. Such studies should be double-blind, compare the active agent to a control, and last a minimum of 6 months. Such a time interval simulates a common recall interval, enables one to utilize a thorough dental prophylaxis at the initiation of the study, and is sufficient time to observe the development of toxic and other side-effects of therapy. The microbiological component should estimate plaque quantitatively and demonstrate that no pathogenic, opportunistic or resistant micro organisms develop. The indices and microbiology should be performed at baseline, and intermediate period and at 6 months. Thus far, published studies meeting these criteria support the efficacy of listerine and chlorhexidine as agents useful in reducing plaque and gingivitis. Preliminary evidence indicates that sanguinarine may also be effective. The most common side effect of listerine was the complaint of poor taste. Increased stain and calculus formation were cited as the most significant side-effects of chlorhexidine. Such side-effects must be taken into consideration when recommending effective antimicrobial mouthrinses for patient use.